JP2004011518A - Intake unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intake unit to improve the accuracy of a flow rate detecting means by setting the intake flow rate in a guaranteed flow rate range of the flow rate detecting means irrespective of the speed or the displacement of an engine. <P>SOLUTION: A flow rate control unit 40 installed between an intake outlet 14 of an air cleaner 10 and an air flowmeter 30 comprises a movable gate 41 to close an intake passage 21 and an actuator 42. The movable gate 41 is driven by the actuator 42 to change an area to close the intake passage 21. When the intake flow rate is small such as that in an idling mode, the intake flow speed through the air flowmeter 30 is increased, and the flow rate detection accuracy by the air flowmeter 30 is improved. Further, when the intake flow rate is large such that in a high-speed operation mode, the sectional area of the intake passage 21 is increased, and pressure losses are reduced. Therefore, the minimum guaranteed flow speed to maintain the flow rate detection accuracy of the air flowmeter 30 is ensured, and the output of the engine is enhanced compatibly. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an intake device for an internal combustion engine (hereinafter, an internal combustion engine is referred to as an “engine”).
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 10-73465, it has been known to use a thermal flow rate sensor as a flow rate detecting means for detecting a flow rate of intake air taken by an automobile engine. The thermal flow sensor detects a change in the amount of heat taken by the intake air flow from a portion heated by the heating resistor or a temperature change in the vicinity of the heated portion to detect an air flow rate.
The flow rate detecting means is generally installed in the intake duct on the air cleaner outlet side, and detects the flow rate of the intake air from which foreign matter has been removed by the air cleaner. Therefore, it is necessary to set the inner diameter of the intake duct in accordance with the guaranteed flow rate range of the flow rate detecting means.
[0003]
[Problems to be solved by the invention]
However, in recent years, the number of revolutions of the engine during idling has been reduced from the viewpoint of reducing the fuel consumption of the engine. As the engine speed decreases, the flow rate of intake air passing through the flow rate detecting means decreases. Therefore, it is necessary to extend the guaranteed flow rate range of the flow rate detecting means to the low flow rate area, and it is necessary to ensure the accuracy of the flow rate detecting means in the low flow rate area.
[0004]
As a method for ensuring the accuracy of the flow rate detecting means in the low flow rate region, it is conceivable to reduce the inner diameter of the intake duct and increase the flow velocity of the intake air flowing in the intake duct. However, when the inside diameter of the intake duct is reduced, the pressure loss of intake air in the intake duct increases. As a result, there is a problem that the output of the engine is reduced and the intake flow rate is insufficient in a high rotation range.
Also, when a plurality of engine displacements are set, the guaranteed flow range of the flow detecting means differs for each engine displacement. Therefore, it is necessary to set the inner diameter of the intake duct for each engine displacement, and it is necessary to change the design of the intake device.
[0005]
Therefore, an object of the present invention is to provide an intake device in which the intake flow rate is set within the guaranteed flow range of the flow detection means regardless of the engine speed or the displacement, and the accuracy of the flow detection means is improved. .
[0006]
[Means for Solving the Problems]
According to the intake device of the first aspect of the present invention, the sectional area of the intake passage is changed by the passage area changing means. Thereby, the cross-sectional area of the intake passage through which the intake air passes is changed according to the intake flow rate. For example, when the rotational speed of the engine is low, such as during idling, the cross-sectional area of the intake passage is reduced, whereby the flow velocity of the intake air is improved. Therefore, it is not necessary to extend the guaranteed flow rate range to a low flow rate area where the accuracy of the flow rate detection means is low. As a result, the intake air flow rate can be set within the guaranteed flow rate range of the flow rate detection means regardless of the engine speed or the displacement. Therefore, the detection accuracy of the flow rate detecting means can be improved.
[0007]
According to the intake device of the second aspect of the present invention, the passage area changing means reduces the cross-sectional area of the intake passage as the intake flow rate in the intake passage decreases. Therefore, for example, when the engine speed is low and the intake air flow rate is small, such as when the engine is idling, the cross-sectional area of the intake passage becomes small, and when the rotational speed is high and the intake air flow rate is large, the cross-sectional area of the intake passage becomes large. When the engine displacement is small and the intake flow rate is small, the cross-sectional area of the intake passage can be reduced. When the engine displacement is large and the intake flow rate is large, the cross-sectional area of the intake passage can be increased. Therefore, it is possible to achieve both the securing of the flow velocity of the intake air passing through the flow rate detection means and the improvement of the output of the engine.
[0008]
According to the third aspect of the present invention, the passage area changing means has a movable weir. The movable weir blocks a part of the intake passage. Therefore, the sectional area of the intake passage can be easily changed by the movable weir.
According to the intake device described in claim 4 of the present invention, the passage area changing means has a driving means for driving the movable weir. Therefore, the sectional area of the intake passage can be easily changed in accordance with the intake flow rate flowing through the intake passage with a simple structure.
[0009]
According to the air intake device described in claim 5 of the present invention, the movable weir is provided on the side facing the flow rate detecting means. Therefore, the area of the intake passage can be reduced without causing a disturbance in the flow of the intake air near the flow rate detecting means. Therefore, the detection accuracy of the flow rate detecting means can be improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an example showing an embodiment of the present invention will be described with reference to the drawings.
1 and 2 show an intake device according to an embodiment of the present invention.
As shown in FIG. 1, the intake device 1 includes an air cleaner 10, an intake duct 20, and an air flow meter 30 as a flow rate detecting means.
[0011]
The air cleaner 10 has a case 11 and an element 12. The air cleaner 10 has an inlet 13 and an outlet 14. The case 11 includes a body 15 and a cap 16, and the element 12 is housed inside a space formed by the body 15 and the cap 16. The intake port 13 is formed in the body 15, and the intake port 14 is formed in the cap 16. The case 11 and the intake duct 20 of the air cleaner 10 are made of resin for weight reduction. The element 12 is a filter for removing foreign substances contained in the intake air, and is fixed inside the case 11. The intake air that has flowed into the air cleaner 10 from the intake inlet 13 passes through the element 12 to remove foreign matter such as silica sand or alumina contained in the intake air, and then flows out from the intake outlet 14 to the intake duct 20.
[0012]
An intake duct 20 is connected to an intake outlet 14 of the air cleaner 10. In the case of the present embodiment, the cap 16 and the intake duct 20 constituting the case 11 of the air cleaner 10 are integrally formed of resin. The intake duct 20 is formed in a cylindrical shape as shown in FIGS. 1 and 2, and forms an intake passage 21 on the inner peripheral side. As shown in FIG. 1, the intake duct 20 has one end connected to the intake outlet 14 of the air cleaner 10 and the other end connected to a throttle valve (not shown).
[0013]
The air flow meter 30 is installed through the intake duct 20. The air flow meter 30 includes a circuit module 31 and a bypass member 32 as shown in FIG. The circuit module 31 is fixed to an outer peripheral portion of the intake duct 20, and a bypass member 32 connected to the circuit module 31 is inserted into the intake duct 20.
The circuit module 31 has a circuit section 33 and a flow rate measuring element section. The circuit section 33 is connected to a thermistor 35 for measuring the air temperature, and a flow rate measuring element section 34 composed of a temperature sensing element and a heating element. The air flow meter 30 is a thermal flow sensor that measures the flow rate of the air flowing through the bypass passage 36 and the flow rate of the intake air flowing through the intake passage 21 based on the power supplied to the heating element and the temperature detected by the temperature sensing element. .
[0014]
The bypass member 32 has a flow measurement pipe 37 protruding toward the center of the intake duct 20 and a venturi pipe 38 formed integrally with the flow measurement pipe 37. The flow measurement tube 37 and the Venturi tube 38 are arranged in parallel to the flow of the intake air. The venturi tube 38 is located at the bottom of the flow measurement tube 37, and a partition wall 39 extends from the venturi tube 38 toward the circuit module 31. The partition 39 forms an inverted U-shaped bypass flow path 36 in the bypass member 32. The flow rate measuring element section 34 is disposed in the bypass flow path 36.
[0015]
The intake duct 20 is provided with a flow control unit 40 as a passage area changing unit. The flow control unit 40 includes a movable weir 41 and an actuator 42 as a driving unit. As shown in FIG. 2, the movable weir 41 closes a part of the intake passage 21 formed inside the intake duct 20. The portion of the movable weir 41 located on the inner peripheral side of the intake duct 20, that is, the intake passage 21 is formed in an arc shape. The end 41 a of the movable weir 41 on the air flow meter 30 side is formed in an arc shape having the same or different radius as the intake duct 20. By forming the end 41a of the movable weir 41 in an arc shape, even when a part of the intake passage 21 is closed by the movable weir 41, the intake passage 21 is approximated to a circular shape. Therefore, the pressure loss of the intake air flowing through the intake passage 21 due to the movable weir 41 is reduced. The movable weir 41 extends from the side of the intake duct 20 facing the air flow meter 30 toward the air flow meter 30. The movable weir 41 is installed on the inlet side of the air flow meter 30, that is, between the air flow meter 30 and the intake outlet 14, as shown in FIG.
[0016]
The actuator 42 changes the cross-sectional area of the intake passage 21 by reciprocatingly driving the movable weir 41 toward the inner circumference or the outer circumference of the intake duct 20, that is, reciprocatingly driving in a direction perpendicular to the axis of the intake duct 20. As shown in FIG. 3, the actuator 42 is driven by a drive signal output from the drive circuit 3 connected to the ECU 2. The ECU 2 receives information on the engine on which the intake device 1 is mounted. The ECU 2 controls the actuator 42 via the drive circuit 3 based on the input engine information. The engine information input to the ECU 2 includes, for example, the engine speed input from the speed sensor 51, the throttle opening input from the throttle sensor 52, the advance amount of the valve timing input from the valve timing sensor 53, and the valve lift. The quantity, the intake air temperature input from the intake air temperature sensor 54, and the cooling water temperature input from the cooling water sensor 55. The ECU 2 is supplied with electric power from a power supply such as a battery 4, and the ECU 2 controls electric power supplied to the actuator 42.
[0017]
The ECU 2 controls the power from the battery 4 to be output to the drive circuit 3 based on the input engine speed, throttle opening, valve timing advance and valve lift, intake air temperature, and cooling water temperature. The ECU 2 sets the position of the movable weir 41 corresponding to the guaranteed flow rate range of the air flow meter 30 from various kinds of input information, and controls the actuator 42 via the drive circuit 3 so that the movable weir 41 moves to the set position. Drive. When the actuator 42 is driven, the position of the movable weir 41 in the intake passage 21 is changed.
[0018]
Next, the flow of intake air in the intake device 1 according to the present embodiment will be described.
Foreign matter is removed from the intake air flowing into the air cleaner 10 from the intake inlet 13 by passing through the element 12. The intake air from which the foreign matter has been removed flows from the intake outlet 14 to an intake passage 21 formed on the inner peripheral side of the intake duct 20. Since the movable weir 41 is provided in the intake passage 21, the flow area of the intake air flowing out of the intake outlet 14 is reduced by the movable weir 41. Thereby, the flow passage area of the intake air is adjusted to an area corresponding to the guaranteed flow rate range of the air flow meter 30 in accordance with the flow rate of the intake air. The intake air flowing out to the intake passage 21 reaches the air flow meter 30 with the flow passage area being narrowed.
[0019]
Next, effects of the intake device 1 according to the present embodiment will be described.
As shown in FIG. 4, the height of the movable weir 41 changes in accordance with the number of revolutions of the engine. The height of the movable weir 41 refers to a distance h from the end 20a of the intake duct 20 on the side opposite to the airflow meter to the end 20a of the arc-shaped end 41a of the movable weir 41 as shown in FIG. . The height of the movable weir 41 decreases as the engine speed increases. As a result, the cross-sectional area of the intake passage 21 increases as the engine speed increases.
[0020]
By changing the cross-sectional area of the intake passage 21 by the movable weir 41, the intake device 1 according to the present embodiment, as shown in FIG. 5, has a characteristic for a conventional small displacement engine and a characteristic for a large displacement engine. It has the combined characteristics. For example, when the rotation speed is low and the amount of intake air taken into the engine is small, the intake passage 21 is closed by the movable weir 41. Therefore, the cross-sectional area of the intake passage 21 decreases, and the characteristics of the intake device 1 approximate to those of a small displacement engine. As a result, it becomes easy to secure the minimum flow rate at which the intake flow rate can be measured while maintaining the minimum guaranteed flow rate of the air flow meter 30, that is, accuracy, and the intake flow rate for securing the minimum guaranteed flow rate decreases. Therefore, the minimum measurable flow rate can be reduced while maintaining accuracy without changing the inner diameter of the intake duct 20.
[0021]
In addition, by having characteristics combining the characteristics for a conventional small displacement engine and the characteristics for a large displacement engine, when the engine speed is high and the amount of intake air sucked into the engine is large, the movable weir 41 closes. The part to be reduced is reduced. Therefore, the cross-sectional area of the intake passage 21 increases, and the characteristics of the intake device 1 approximate to those for a large displacement engine. As a result, the sectional area of the intake passage 21 is sufficiently ensured, and the pressure loss is reduced as shown in FIG.
Further, as shown in FIG. 5, it is easy to secure the minimum guaranteed flow velocity, so that the flow velocity of the intake air flowing through the air flow meter 30 can be set within a high stability range as shown in FIG. Therefore, the detection accuracy of the intake flow rate can be improved.
[0022]
As described above, in one embodiment of the present invention, the position of the movable weir 41 is changed according to the engine speed. Therefore, the area of the intake passage 21 is changed according to the engine speed. As a result, the intake flow rate is set within the guaranteed flow rate range of the air flow meter 30 irrespective of the engine speed or the displacement. Therefore, the detection accuracy of the air flow meter 30 can be improved. In addition, by moving the movable weir 41 in accordance with the displacement of the engine or the number of revolutions of the engine, the cross-sectional area of the intake passage 21 at the time of high engine revolution can be enlarged. Therefore, it is possible to reduce the pressure loss of the intake air, and it is possible to ensure the minimum guaranteed flow velocity of the air flow meter 30 and achieve the output of the engine at the same time.
[0023]
In the embodiment of the present invention described above, an example in which the movable weir has an arc shape has been described. However, the movable weir is not limited to the arc shape but may be a semicircle shape or any other shape. Further, the movable weir can be installed at an arbitrary position where the flow is hardly disturbed in accordance with the flow of the intake air.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a part of an intake device according to an embodiment of the present invention.
FIG. 2 is a sectional view taken along line II-II of FIG.
FIG. 3 is a block diagram showing a driving unit for driving an actuator of the intake device according to one embodiment of the present invention.
FIG. 4 is a schematic diagram showing a relationship between an engine speed and a movable weir in an intake device according to an embodiment of the present invention.
FIG. 5 is a schematic diagram showing a relationship between an intake flow rate and a flow rate of an air flow meter in the intake device according to one embodiment of the present invention.
FIG. 6 is a schematic diagram showing a relationship between an intake flow rate and a pressure loss in the intake device according to one embodiment of the present invention.
FIG. 7 is a schematic diagram showing a relationship between an intake flow rate and output stability of an air flow meter in the intake device according to one embodiment of the present invention.
[Explanation of symbols]
1 intake device 14 intake outlet 20 intake duct 21 intake passage 30 air flow meter (flow rate detecting means)
40 Flow control unit (passage area changing means)
41 movable weir 42 actuator (drive means)

Claims (5)

An intake duct connected to an intake outlet side of the air cleaner and forming an intake passage through which intake air discharged from the air cleaner flows;
Flow rate detection means installed in the intake duct, detecting an intake flow rate flowing through the intake duct,
On the air cleaner side of the flow rate detecting means, a passage area changing means capable of changing a cross-sectional area of the intake passage,
An air intake device comprising: 2. The intake device according to claim 1, wherein the passage area changing unit decreases the cross-sectional area of the intake passage as the flow rate of intake air flowing in the intake passage decreases. The intake device according to claim 1, wherein the passage area changing unit includes a movable weir that closes a part of the intake passage and changes a cross-sectional area of the intake passage. 4. The intake device according to claim 3, wherein the passage area changing unit includes a driving unit capable of reciprocatingly driving the movable weir in a direction substantially perpendicular to an axis of the intake passage. The intake device according to claim 3, wherein the movable weir is provided on a side of the intake duct facing the flow rate detection unit.

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